Lesson 42.3 · Pattern Recognition Drills
How to Drill
Give yourself two minutes to name the pattern and say why, ten more to sketch the approach, then check. Keep a log of misses and revisit them after 1, 3 and 7 days.
8 min
Think of it like this
Learning bird calls: you don't memorise a book, you listen to mixed recordings, guess, check, and replay the ones you got wrong until they stick.
1.A routine that works
1. Read the problem once, slowly. 2. Name the pattern and one sentence of reasoning ("contiguous + longest + condition on contents → variable sliding window"). 3. Sketch the approach and its complexity. 4. Reveal and compare. 5. If wrong, write the clue you missed in a notebook.
Mix topics deliberately: alternating patterns forces recognition, while doing ten problems of one pattern only trains execution. Revisit missed problems on a schedule (spaced repetition); the Interview module (44) has a revision plan.
Remember
- Name it, justify it, then reveal.
- Log the missed clue.
- Mix topics; space the reviews.
Common mistakes
- Revealing immediately (the guess is the exercise).